What is the unit of thermal conductivity ?

Related Mcqs:

1. The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of ‘a’ in SI system will be________________?

   A. W/m.k
   B. W/m
   C. W/m.k2
   D. None, ‘a’ is just a number

2. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally ?

   A. Decreases
   B. Increases
   C. Remains unchanged
   D. Increases exponentially

3. Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

   A. 35.5
   B. 43.75
   C. 81.25
   D. 48.25

4. In SI units, thermal conductivity is expressed in__________________?

   A. Watt/m.°K
   B. Watt/m2. °K
   C. Watt/m2. °K
   D. Watt/m4. °K

5. Thermal conductivity of a gas at low density, ___________ with increase in temperature ?

   A. Decreases
   B. Increases
   C. Remains unchanged
   D. May increase or decrease; depends on the gas

6. A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2.K. The Biot number is ______________?

   A. 5.6
   B. 0.025
   C. 3.5
   D. 0.0035

7. Which of the following has the highest thermal conductivity ?

   A. Brick
   B. Air
   C. Water
   D. Silver

8. _____________ equation relates the thermal conductivity of a solid to its temperature ?

   A. Antoine
   B. Kopp’s
   C. Lee’s
   D. Kistyakowsky

9. With increase in temperature, the thermal conductivity of steel___________________?

   A. Increases
   B. Decreases
   C. Remains unchanged
   D. Increases exponentially

10. Among liquids, water has a comparatively high value of thermal conductivity, due to its__________________?

    A. Low density
    B. High viscosity
    C. Partial ionisation
    D. Dense structure